Also known as "time deposits," certificates of deposit (CDs) are an insured bank product that pays a fixed rate of interest for a specified period of time (e.g., 18 months). Typical CD maturities range from seven days to five years, with higher rates of return paid on CDs with longer maturities. A penalty is assessed if funds are withdrawn prior to maturity, resulting in the loss of a certain number of days of interest (the amount varies among financial institutions). If an early withdrawal penalty exceeds the interest earned, the difference will be deducted from an investor’s principal.

Many people think that CDs can only be purchased at banks. Many credit unions and full-service brokerage firms also sell federally insured CDs to investors. Investment firms purchase the CDs of banks nationwide in large blocks and sell them to investors in small denominations. The difference between their buying and selling price, called "the spread," is how they make a profit. Since brokers shop the entire country for high yields, brokered CDs often pay more attractive rates than CDs at local banks. CDs can be redeemed prior to maturity, often without penalty, but, due to interest rate risk, the value of a brokered CD can be higher or lower than someone’s initial investment.

Another relatively new type of CD is the equity-indexed CD. Sold through both banks and brokers, these CDs base returns, in part, on appreciation of a stock market index like the Standard & Poor’s 500 (S&P 500). Many require a $5,000 initial investment (often less for IRAs). Unfortunately, equity-indexed CDs rarely include the full appreciation potential of the S&P 500 because they exclude the portion derived from company dividends. Many also cap the maximum growth rate, which further reduces upside potential. As a result, most financial advisors suggest avoiding these CDs and buying regular CDs for income and a stock index fund for capital growth.